The instant invention relates to surgical devices and more particularly to a surgical device for use in the treatment of unilateral vocal cord paralysis.
Unilateral vocal cord paralysis is a relatively common disorder in which one of the two vocal cords becomes paralyzed. Such paralysis most often occurs when the recurrent laryngeal nerve on one side of the neck is injured by surgery, trauma or a tumor. When the laryngeal nerve is damaged, the associated vocal cord no longer functions normally, and it rests flaccidly to the side of the larynx. The remaining vocal cord is functional. However it cannot cross over the mid-line of the larynx to press against the paralyzed vocal cord and form sounds properly, and therefore these patients have a hoarse breathy voice, have difficulty raising their voices or coughing, and often aspirate fluids when swallowing.
It has been found that unilateral vocal cord paralysis can be corrected by artificially moving the paralyzed vocal cord toward the mid-line of the larynx where the functional vocal cord can press against it. One known treatment for manipulation of the paralyzed vocal cord comprises injecting the paralyzed vocal cord with aliquots of TEFLON (registered TM of Dupont) paste which effectively expand the vocal cord toward the mid-line of the larynx. A surgical procedure has also been developed wherein the surgeon approaches the patient's thyroid cartilage externally, and cuts a small rectangular window in the thyroid cartilage to create a rectangular panel of cartilage adjacent to the paralyzed vocal cord. Theoretically the cartilage remnant reduces the risk of erosion of the prosthesis, but the reported experience of surgeons who remove the cartilage is that there have been no complications and that the surgeons believe that the vocal quality of the patients is improved with this technique. In either case, the soft tissue, including the paralyzed vocal cord, can then be pressed into the laryngeal airway until the patient can phonate optimally. In the existing technique a silastic shim is then estimated in size and shape and cut to fill the window and to hold the soft tissue and vocal cord in position. The block is then secured to the thyroid cartilage with sutures or flanges.
The technique of vocal medialization with a silastic shim has two clear advantages over the TEFLON paste injections. First, the silastic prosthesis can be removed and replaced with a different size prosthesis if airway or vocal cord problems occur. Second, the silastic implant also avoids the migration of Teflon paste or the formation of granulation tissue.
The major drawback to both of these procedures is that they are not easily adjusted to the individual dimensions of each patient's larynx. In other words, it is difficult to fine-tune the patient's optimal voice with either of these techniques. On the one hand, the Teflon technique makes it difficult to estimate the exact amount and location of each aliquot of paste. On the other hand, it is difficult to customize the shape of the silastic block during the surgical procedure. There has also been described an adjustable medialization technique which relies on an implanted balloon, but the theoretically less precise expansion of a balloon and risk of leakage make this alternate technique potentially less attractive.